Noise produced by unsteady flow around aircraft structures, termed airframe noise, is a significant source of aircraft noise during approach and landing. Sound radiated from the aircraft undercarriage is a major contributor to airframe noise. In many or most instances, noise generated by landing gear is dominated by cavity (wheel well) noise at low- to mid-frequencies.
Various approaches have been utilized in an attempt to reduce noise generated by aircraft undercarriage. One approach seeks to reduce noise by hindering the development of large scale structures within the free shear layer and to disrupt their spanwise coherence at the cavity leading edge. Such concepts include leading edge serration, application of micro perforations at the cavity lip, and leading edge deflectors/spoilers. Other known concepts utilize active flow control strategies such as blowing, suction, and micro-actuators.